LCD devices have the advantages of portability, low power consumption, and low radiation, and because of this they have been widely used in various portable information products such as notebooks, personal digital assistants (PDAs), video cameras, and the like. Furthermore, LCD devices are considered by many to have the potential to completely replace CRT (cathode ray tube) monitors and televisions.
Referring to FIG. 6, a typical LCD device 6 is schematically shown. The LCD device 6 includes an LCD panel 60, and a backlight module 62 for illuminating the LCD panel 60. The LCD panel 60 includes a first substrate assembly 64, a second substrate assembly 66 parallel to the first substrate assembly 64, and a liquid crystal layer 65 sandwiched between the two substrate assemblies 64, 66. The backlight module 62 is provided adjacent to the first substrate assembly 64.
Referring also to FIG. 7, the first substrate assembly 64 includes a first transparent substrate 641, a number n (where n is a natural number) of gate lines 642, a number m (where m is also a natural number) of data lines 643, a plurality of thin film transistors (TFTs) 646, and a plurality of pixel electrodes 645.
The gate lines 642 are parallel to each other, each gate line 642 extending along a first direction. The data lines 643 are parallel to each other, each data line 643 extending along a second direction orthogonal to the first direction. The gate lines 642 and the data lines 643 cross each other, thereby defining a plurality of pixel regions 644. The pixel electrodes 645 are disposed in the pixel regions 644, respectively.
Each TFT 646 is provided in the vicinity of a point of intersection of a corresponding gate line 642 and a corresponding data line 643. The TFT 646 includes a gate electrode 647 connected to a corresponding gate line 642, a source electrode 648 connected to a corresponding data line 643, and a drain electrode 649 connected to a corresponding pixel electrode 645.
Referring also to FIG. 8, the second substrate assembly 66 includes a second transparent substrate 661, and a color filter 662 disposed on an inner surface of the second transparent substrate 661 that is nearest to the liquid crystal layer 65. The color filter 662 includes a black matrix 6621 and a color region 6622. The color region 6622 includes a plurality of red filter units, green filter units, and blue filter units arranged in a matrix and separated by the black matrix 6621. The red, green, and blue filter units correspond to the pixel electrodes 645 on the first transparent substrate 641, respectively. The black matrix 6621 spans areas of the second transparent substrate 661 that correspond to the gate lines 642, the data lines 643, and the TFTs 646 of the first transparent substrate 641.
Areas of the LCD device 6 corresponding to the gate lines 642, the date lines 643, and the TFTs 646 cannot display images properly, because no appropriate electric field is generated in those areas. The black matrix 6621 is used to absorb light that transmits through such areas, in order to improve the display quality.
Because the liquid crystal layer 65 does not emit light itself, the LCD device 6 needs the backlight module 62 to illuminating the LCD panel 60. This means the LCD device 6 has relatively high electrical power consumption.
Furthermore, the black matrix 6621 is generally made a little larger than the areas of the LCD device 6 that cannot display images properly, because of positioning tolerances that are needed when the first and second transparent substrates 641, 661 are attached together during manufacture of the LCD device 6. Thus the areas of the red filter units, the green filter units, and the blue filter units are correspondingly reduced in size. As a result, an aperture ratio of the LCD device 6 is correspondingly low. Accordingly, the capability of the LCD device 6 to display good quality images is limited.
What is needed, therefore, is an LCD device that can overcome the above-described deficiencies.